Successful Water Conformance Control Using Newly Developed Smart Polymer Gels for Water Shutoff Application

Abstract

Abstract Water conformance is a common challenge in oilfield industry especially in water flood and active water drive reservoirs where water production has a significant impact on production economics, oil recovery and facilities constraints. Water shut-off (WSO) is an essential solution to delay or minimize water production however effectiveness depends on treatment efficiency. Selective mechanical water shut-off, (i.e. through tubing bridge plug with cement on top, mechanical plugs), the main technique used to solve this problem so far, has disadvantages, mainly sacrificing the section below the plugs in spite of having hydrocarbons below the plugs. A new and innovative treatment solution using chemical water shut-off was developed in-house, which when used, led to minimizing the unwanted water production with enhanced oil production consequently helping to improve economic life of wells. The novel and fit-for-purpose chemical water shut-off technology extends the limitations of the currently available materials. The new system is designed to chemically bond the polymer to the rock surface. So, the system will have enhanced stability with superior performance. The fluid system is low-toxic and environmentally friendly. It is comprised of polymer gel and adsorption components. The gelant can be placed as a single phase, low-viscosity solution into the targeted formation zones. The gelation process is activated by the formation temperature. In-situ gelation takes place and the gel plugs pore spaces, thereby limiting undesired water production. The system can effectively prevent water flow at wide temperature range. The gelation time can be controlled by tuning the fluid composition. It allows a predictable and controllable pumping time, ranging from hours to days at a given temperature. Post job, the well performance improved substantially with significant reduction in water production and consequent increase in the oil production. Production logs conducted pre and post operation have clearly confirmed shutting off the high permeable streaks which were contributing to high water production. With the changed production profile and rate test pre and post job, the technology was confirmed a success. In addition cleanout of the treatment fluid performed after the treatment, ensured full-bore accessibility of the lateral for future well intervention including logging operations. This paper will describe in details the novel technology and its application, solution selection process and the operational deployment of the chemical including real-time monitoring of the fluid, as well as precautions taken to increase the success percentage.